JPH0761325B2 - Method and apparatus for evaluating interest in visual stimulation - Google Patents

Description

The present invention relates to a device for evaluating interest in visual stimuli (attention monitor) and a method for evaluating interest in visual stimuli.

More particularly, the present invention relates to methods and devices for monitoring a subject's level of attention to visual stimuli. The results obtained by the method and device of the present invention include:
It provides useful objective information about the subject's attention or interest in visual display information such as pictures, posters and the like. This rating is then used to modify advertisements, pictures, posters, etc. to make them more attractive and attract the viewer's attention.

According to the present invention, a control signal that produces an identifiable response in a subject is used in combination with the visual stimulus to assess the subject's interest in the visual stimulus, and the control signal based on the change in the response is used. A method for evaluating interest in a visual stimulus of a subject, which is performed by measuring interest of an examiner, comprising: displaying a periodic visual control signal having a predetermined frequency; Detecting the electroencephalogram (EEG) signal of the subject, analyzing the EEG signal, and measuring the magnitude of the component of the EEG signal corresponding to the frequency of the control signal, The control signal and the visual stimulus are simultaneously displayed on the subject, the EEG signal is detected and analyzed, the magnitude of the component is measured during the simultaneous display, and the change in the magnitude of the component of the EEG signal is measured. Measure and according to the changes A method is provided, characterized by assessing a subject's interest in said visual stimulus.

It has been found to discriminate visual [noise] or flicker signals when the human brain concentrates on other visual information. Therefore, in the above method, the brain discriminates the visual control signal presented as the visual [noise] signal or the flicker signal, and the method of the present invention accurately evaluates the EEG response to the visual control signal and accurately determines the decrease amount of the amplitude. You can This gives a measure of the brain's interest in visual stimulation.

Preferably, the visual control signal comprises one component and the change in magnitude of said component in the EEG signal is determined by using an analytical technique capable of isolating a sinusoidal component of known frequency from the background signal. It

According to one form of the invention, the visual stimulus is displayed on a TV screen and the visual control signal is superimposed on the visual field of the subject and preferably comprises a visible light signal. The intensity of the optical signal varies at precisely known sinusoidal frequencies. Alternatively, the control signal may be in the form of a visual noise signal or flicker displayed on a television screen. Alternatively, it may include a sinusoidal change in screen brightness. In yet another form, a liquid crystal screen may be inserted between the observer and the television screen so as to change the transmitted light into a sine wave at a constant sine wave rate.

The present invention also uses a control signal that produces an identifiable response within a subject in combination with a visual stimulus, and measures the subject's interest based on changes in the response to assess the subject's interest. An apparatus for evaluating interest in a visual stimulus, a means for generating a visually recognizable periodic control signal having a predetermined frequency, a display means for displaying the visual stimulus, and a visual control for a subject. A means for extracting the EEG signal from the subject while simultaneously observing the signal and the visual stimulus, and one state in which the subject sees the control signal and another state in which both the control signal and the stimulus signal are seen. To analysis means for measuring the change in the magnitude of the component of the EEG signal due to the periodic control signal, wherein the analysis means includes a discrimination means for discriminating from the component of the EEG signal that is not at the predetermined frequency. Characterized by According to one arrangement, the means for generating a visually recognizable control signal comprises a subject and a display means for adding a light component or for attenuating light transmitted through the screen. Includes a screen inserted between and. For example, the generating means may include a semi-reflective screen through which the display means may be seen through and the screen being configured to reflect control signals to the subject.
Alternatively, the control signal generating means may include a liquid crystal screen controlled to attenuate the transmitted light.

Also, the display means and the means for generating visually recognizable control signals may comprise a single display element, for example a television screen. in this case,
The control signal is superimposed on the visual stimulus displayed on the television screen. For example, the control signal may include a periodic intensity of screen brightness.

The present invention will be described in more detail below with reference to the accompanying drawings.

FIG. 1 is a schematic explanatory view of an attention monitor embodying the present invention.

FIG. 2 is a schematic plan view showing the positions of the EEG electrode and goggles of the present invention.

FIG. 3 is a more detailed block diagram of the control signal generator.

FIG. 4 is a diagram of a circuit for controlling the intensity of the LED array.

FIG. 5 is a schematic diagram of an LED array.

FIG. 6 is a schematic side view of an LED array having a shield.

FIG. 7 is a more detailed schematic diagram of the EEG receiver circuit.

FIG. 8 is a circuit diagram of a part of the circuit shown in FIG.

9A, 9B, and 9C are waveform diagrams useful for understanding the operation of the circuits of FIGS. 7 and 8.

Figure 10 shows steady-state visually evoked potentials (SSVEP).
11A, 11B, and 11C are detailed partial views of the chart of FIG. 10.

The attention monitor device shown schematically in FIG. 1 is used for measuring the interest of the subject 2 in the visual information displayed on the television screen 4.
The EEC electrode is attached to the head of the subject and is connected to the receiver 8 by the input line 6. The receiver is a computer 12
Amplification and other processing before transmission to the. The computer 12 is connected to a disk storage unit 13 and a visual display unit 15 and, if necessary, a printer. The device further includes a stimulus generator 14, which provides control signals to the left and right LED arrays 16. The LED array is preferably carried on goggles 17, which are worn by the user 2 during use. In practice, multiple subjects may wear goggles 17 to perform testing on multiple subjects at the same time.

As shown in FIG. 2, the gokule 17 includes an arm 18 and a cross piece 20. These may support the goggles on the user's ear and nose. Alternatively, elastic headbands may be used for this purpose. The goggles have a pair of semi-reflective screens 19, which are positioned at an angle of about 45 degrees to the user's line of sight during use. The screen is
The user can directly see the television screen 4 through the screen, and the left and right attached to the arm 18
The LED array 16 is configured to reflect light to the subject's eyes.

FIG. 5 is a schematic explanatory view of an example of the arrangement of the LED array 16. The array includes seven LEDs 128 arranged in a circle.
Each array has inner and outer shields 138, 140 to substantially eliminate electric and magnetic fields up to the array that may be generated by current. These staging areas are the EEG for subjects.
This is because it has an unfavorable effect on the electrodes. The leads 142 to the LED array are also shielded for the same reason.

In general, the system works as follows. The stimulus generator 14 produces a control signal at a precise known frequency, for example in the range 8-15 Hz. Preferably the frequency is 10 Hz. led
A reference frequency is used to modulate the intensity of the optical output of array 16. The subject receives the intensity-modulated reflected red light from the screen 19 at the reference frequency. Initially, no information is displayed on the television screen 4 and the EEG signal in this state is obtained. The receiver 8 and the computer 12 are arranged to isolate the components occurring at the reference frequency from the received EEG signal, the magnitudes of these components being stored in the disk storage unit 13. This information occurred
Provide the subject's criteria for the normal amplitude of the EEG signal. The system then operates as before, but this time a visual stimulus is being applied to the television screen 4. For example,
The television advertisement is projected on the screen and the composite EEG signal is received and processed by receiver 8 and computer 12. The system is arranged to isolate the component of the EEG signal at the reference frequency and store its magnitude in the disk storage unit 13. Therefore, the disk storage unit 13
The information obtained at can be used to measure the reduction of the magnitude of the reference frequency component when the advertisement is projected on the screen as compared to when the advertisement is not projected on the screen. The measure of size reduction is an objective measure of the subject's interest in the advertisement. This is because the brain of the subject discriminates unnecessary information when the subject focuses his attention on other visual information.

As will be described below, the EEG information is sampled relatively quickly and all of the sampled information is stored in unit 13. This allows evaluation of each of a series of scenes of the advertisement displayed on the screen 4. Furthermore, it is possible to observe the advertisement displayed on the television screen 4 by a large number of subjects at the same time, for example 25 subjects, in order to know a substantially correct aspect of a similar response to an advertisement. Varying the number of subjects, the number of advertisements and stimuli projected, the amount of information stored, and the type of analysis performed on the information in order to objectively measure the subject's interest in the projection target. Can be changed.

FIGS. 3 to 11 show in more detail an example of a device for measuring the interest of a large number of subjects with respect to the advertisement projected on the television screen 4.

FIG. 3 shows the circuit configuration of the stimulus generator 14 in more detail. The circuitry includes a crystal controlled oscillator 36, which may be, for example,
Has a stable frequency of 4MHz. The output of the oscillator enters a divider, the output of which is at a reference frequency, for example in the range 1-100 Hz, preferably 10 Hz. The output of the divider 38 is an LED
Connected to the control circuit 90, there is one circuit 90 for each set of goggles 17. The output of each circuit 90 enters the left and right LED arrays 16 and the diodes 128 of the arrays are connected in series.

FIG. 4 shows one specific example of the LED control circuit 90. Divider 3
The output of 8 is connected to the input line 120, which is the circuit 90
Is connected to the input of amplifier 122 through zero conditioning network 124, which is tuned to have the desired DC level.
The output of amplifier 122 is connected to the input of a current buffer 126 for exciting LED array 16. Each array 16 includes seven LED devices 128 arranged in a circle, as shown schematically in FIG. 14 LEDs connected in series, buffered
It is excited by the current supplied from 126. The other end of the series LED is connected to the negative feed line 130, the value of which is fixed and selected according to the number of LEDs connected in series. Control LED 1 to adjust the intensity of the output of array 16
32 are connected in series and are arranged to illuminate a phototransistor 134, the output of which is connected via amplifier 136 to the input of amplifier 122. The output of the control LED 132, chosen to be the same type used in the array 16, represents the luminous intensity output of the array, which is used as negative feedback to control the peak intensity reached by the LED array 16. It Thus, circuit 90 ensures the intensity of the light output from LED array 16 at the same average level, regardless of frequency. According to one configuration, Stan
LED known as ESBR diode manufactured by Ley
The use of the device has proven to be advantageous. The current through the diode is typically 20-30 milliamps and less than 50 milliamps. The zero regulation circuit ensures that the LED device is not reverse biased at any stage of the process. This is because reverse bias causes input confusion for otherwise purely sinusoidal LED devices. Feedback LED 132 also ensures that the intensity of the light output from array 16 is a linear function of the current input to the array, thereby
The intensity of the light emitted by array 16 has a reference frequency of 10 Hz
Secure to change in.

FIG. 2 shows a preferred arrangement of EEG electrodes for obtaining an EEG signal from the subject 2. In this arrangement, the pair of electrodes 21, 23 are connected to the subject's ear. The ground electrode 25 is connected to the subject's forehead and the six further electrodes 27,29,31,33,35,37 are arranged according to the table below. The code name of the part is the international agreement 10-
According to 20 (Inter-national 10-20 Convention). Another site that can be used is between sites T3 and T5 and between sites T4 and T6.

Table 1 Electrode part 27 0 ₁ Left side of occipital area 29 0 ₂ Right side of occipital area 31 P ₃ Left side of top of head 33 P ₄ Right side of head of head 35 F ₃ Left side of front head 37 F ₄ Right side of front head 25 Fpz Forehead central part Ground Fig. 7 The structure of the receiver 8 is shown in more detail. Each subject 2
It will be appreciated that has a receiver circuit 39 which receives the input from the EEG electrodes via line 6. Each receiver circuit 39 has an EE
Each G electrode 27, 29, 31, 33, 35, 37 has one amplifier 144. The output of the amplifier is connected to a bandpass filter 146 having a passband in the range 1-100 Hz. The output of the filter 146 is connected to each sample and hold circuit 172, and the output of the sample and hold circuit is an analog multiplexer.
It is connected to 186. The receiver 8 includes a frequency multiplication circuit 173 which receives the input from the divider 38 via line 177 and outputs the output of the filter 146, for example 32 times every cycle.
It functions to control the sample and hold circuit 172 at a sampling rate of 320 times per second, ie 320 times per second.

The output line 179 of the multiplier 173 is connected to another frequency multiplier 175, which controls the operation of the multiplexer 168 for all sample and hold circuits coupled to all subjects.
The output of 172 is sequentially transferred to the analog-digital converter 184 and the computer 12.

FIG. 8 is a more detailed illustration of one of the EEG electrodes (as shown in FIG. 2), eg, the amplifier 144 of electrode 27, filter 146, and sample and hold circuit 172. In this configuration, the ground electrode 25 is connected to the ground input 192 of the amplifier 192. Electrodes 21, 23 (electrically connected to each other) are connected to the negative input 188 of the amplifier. Electrode 27 is connected to positive input 190 as shown. Amplifier 144 may include a precision manipulated differential amplifier AMP-01. Inputs 188, 190 include coupling capacitors 194 that can wave very low frequency components, eg, less than 1 Hz, and thus may be considered part of filter 146. The output of amplifier 144 enters the resistor-capacitance network. The network includes the rest of filter 146 and serves to attenuate frequencies above 100 Hz, for example. The output of filter 146 is then amplified by a pair of amplifiers 196,198. The latter includes DC offset network 200 for adjusting the DC output level of output amplifier 198. The output of amplifier 198 is connected to the input of sample and hold circuit 172.

FIG. 9A shows a typical reference waveform at 10 Hz. A waveform 218 shown in FIG. 9C is a waveform suitable for controlling the sample hold circuit 172. The waveform includes a negative pulse 217 that occurs at a rate 32 times that of the reference waveform 216 (FIGS. 9B and 9C have a different time scale than 9A). The rising edge of the negative going pulse 217 causes the sample and hold circuit 172 to track the output of the filter 146, as shown by the locus portion 219. Pulse rise 217
Initializes the start of the hold cycle as shown by waveform 226 in Figure 9B. The output of the sample and hold circuit 172 is multiplier 1
It is transferred to the analog-to-digital converter 184 via the multiplexer 186 at a rate controlled by 75, which causes the entire circuit 172 to be sampled and stored in the disk storage unit 13.

Since the waveform of the reference frequency is exactly known, the computer 12
The program in can be configured to mathematically isolate the components in each EEG signal received by the amplifier 144 at the reference frequency using Fourier analysis techniques. The reference frequency waveform may be input directly from the stimulus generator 14 to the computer 12 or may be pre-programmed in the computer.

In general, for each of the EEG waveforms f (t), that is, for the output of each sample and hold circuit 172, sin 2πF ₁ t and co
s2πF ₁ t is multiplied. However, F ₁ is the reference frequency.
The sine and cosine products are integrated over many complete cycles. Thereby, the size M can be calculated by the following formula.

However, computer 12 receives the digitized variant of output waveform 226 of circuit 172 and therefore a digital approximation of the integral is used as is known in the computer industry.

For each electrode 27, 29, 31, 33, 35, 37 for each subject, the value of the frequency component of the reference frequency 10 Hz when nothing is projected on the television screen 4 is first calculated. This value is referred to as the steady-state visual evoked potential SSVEP for each electrode. Therefore, this value is used as a reference level to compare the corresponding values of the reference frequency components when the advertisement is being projected and to confirm the magnitude reduction. An example of the calculation execution method will be briefly described below with reference to FIG. 10 and FIGS. 11A to 11C.

In one embodiment, G subjects 2 are used to pretest the advertisements and each advertisement is projected on television screen 4 three times according to the following protocol.

However, {circle around (B ⁱ ₁₁₎ } indicates the first blank period (30 seconds) of the first sequence for the subject i.

(C ⁱ ₁₁ ) indicates the first advertisement period (30 seconds) of the first sequence for the subject i.

Received by the receiver 8 of data during the recording sequence,
It is analyzed by the computer 12 and stored in the disk unit 13. It will then be analyzed in more detail at a later stage.

After collecting the data in the above sequence, the computer 12 is used to objectively assess the subject's interest in the advertisement. The first step is a step of measuring SSVEP in the first sequence of the blank display for each subject, that is, the sequence ▲ B ⁱ ₁₁ ▼. For convenience, SSVEP of each subject is indicated by ▲ F ^g _1B ▼. .

The next step is the expression Is used to calculate the standardized mean response of all subjects. However, SL ^g (Cij) in the equation = EEG recorded in the display of the J-th advertisement of the i-th sequence of the subject g
Slicing the data The next step is to measure the magnitude of the EEG response at each electrode site and the reference frequency for the advertisement while the advertisement is being displayed, from which the standardized average response is subtracted to obtain the magnitude change. Thus, this size change corresponds to the subject's interest in the projected advertisement.

FIG. 10 is a schematic diagram of a flowchart for evaluating SSVEP size of N slices of EEG data from a specific EEG electrode recording region. 11A, 11B and 11C show the steps of the flowchart of FIG. 10 in more detail.

The following terms and parameters are used in the flow chart.

The number of arrays (usually 512, 1024 or 2048) stored in the SL disk unit 13, the number of elements in the NE slice hereafter referred to as a "slice" SL ^g Slice SL (n ) Nth slice SL (i, n) ith point of slice n SL ^g (Bij) slice SL of EEG data recorded during observation of the Jth blank period of the ith sequence of subject g (SIN) Slice SL with sine reference waveform (COS) Slice with cosine reference waveform NC NC Number of complete cycles of reference waveform (10Hz) during slice duration, typically NC = 25 cycles SL (z) sine reference waveform Slice with zero crossing point at positive slope of SL (m) Slice with magnitude of SSVEP over time SL (F) Slice with phase of SSVEP over time The information generated by the analysis used above is projected. Various tests for adverts It is of use as an objective evaluation of interest. In addition, we observe, for example, 10 segments of each advertisement, confirm the viewer's interest in the segment,
It is also possible to get useful information about the reaction to different parts of the advertisement. Of course, it is also possible to modify the advertisement using the obtained information and create a target product that is more effective as an advertisement. It is also possible to discriminate between the different types of evoked responses by considering the power generated by different EEG electrode sites on the subject.
Of course, this kind of information is useful when you want to give a specific effect to an advertisement.

It will be apparent to those skilled in the art that various modifications can be made within the spirit and scope of the present invention.

 ─────────────────────────────────────────────────── --Continued front page (56) Reference JP-A-48-41577 (JP, A) US Patent 4216781 (US, A) US Patent 4203452 (US, A) US Patent 2860627 (US, A) US Patent 3901215 (US, A) US Patent 3032029 (US, A) US Patent 4493327 (US, A)

Claims (20)

[Claims] 1. A subject to be evaluated by using a control signal that produces an identifiable response in the subject in combination with a visual stimulus and measuring the subject's interest based on changes in the response. A method of evaluating interest in visual stimuli, the method comprising: displaying a periodic visual control signal having a predetermined frequency; and detecting an electroencephalogram (EEG) signal of a subject looking at the visual control signal. And analyzing the EEG signal and measuring the magnitude of the component of the EEG signal corresponding to the frequency of the control signal, the control signal and the visual stimulus being simultaneously displayed to the subject. , Detecting and analyzing the EEG signal, measuring the magnitude of the component during the simultaneous display, measuring the change in the magnitude of the component of the EEG signal, according to the change of the subject to the visual stimulus. Characterized by evaluating interest Evaluation method of interest in visual stimuli of subjects. 2. The method of claim 1, wherein the visual control signal comprises a sinusoidal signal. 3. The method of claim 2, wherein the visual control signal is a red light signal of varying intensity. 4. The semi-reflective screen is disposed between the subject and the visual stimulus source, and the visual control signal is reflected in one or both eyes of the subject. the method of. 5. The method of claim 4, wherein the visual stimulus signal is displayed on a television screen. 6. The method of claim 5, wherein the visual stimulus is advertising material. 7. The method of claim 6, wherein the advertising material is modified and displayed to elicit a higher level of interest in the subject. 8. The method of claim 6, wherein the advertising material is displayed to multiple subjects simultaneously and the responses of each individual are averaged. 9. The method is repeated for each of a plurality of subjects, and the change in magnitude for each subject is measured for each individual subject's control signal only display. Calculating a standardized average response from the magnitudes of the components of the EEG signal measured, and the components of the EEG signal measured for simultaneous display of control signals and visual stimuli to each individual subject. And a standardized mean response is subtracted from the magnitude of the. 10. A subject to be evaluated by using a control signal that produces an identifiable response in the subject in combination with a visual stimulus and measuring the subject's interest based on changes in the response. A device for evaluating interest in a visual stimulus, comprising means for generating a visually recognizable periodic control signal having a predetermined frequency; display means for displaying the visual stimulus; A means for extracting the EEG signal from the subject while simultaneously observing the control signal and the visual stimulus, and one condition in which the subject sees only the control signal and the other one who sees both the control signal and the stimulation signal The state and the analysis means for measuring the change in the magnitude of the component of the EEG signal due to the periodic control signal, said analysis means for discriminating from the component of the EEG signal which is not the predetermined frequency. Including An apparatus for evaluating interest in visual stimuli of a subject, characterized by. 11. The means for producing a visually recognizable signal comprises a red light ray source and means for sinusoidally varying the intensity of the light ray at a predetermined frequency.
The apparatus according to item 10. 12. The device according to claim 10, wherein the frequency is 1 to 100 Hz. 13. The device of claim 12, wherein the frequency is about 10 Hz. 14. The apparatus of claim 10, wherein the means for generating a visually recognizable signal comprises an LED array. 15. The device according to claim 14, wherein the LED array is mounted on a spectacle frame. 16. The display means includes a television screen, the spectacle frame includes a reflective screen so that the subject can view the television screen directly, and the screen directs light rays from the LED array to one eye of the subject. 16. A device according to claim 15, characterized in that it also reflects towards both eyes. 17. The apparatus according to claim 10, wherein the discrimination means includes a sample hold circuit, and the sample hold circuit holds the output value of the EEG signal at the end of each cycle of the frequency component of the stimulus. . 18. The apparatus according to claim 10, wherein the discriminating means comprises an arithmetic unit for calculating the magnitude M _n of the EEG signal of the frequency by calculating the square root of the sum of the squares of the output values. . 19. A device used to evaluate a subject's interest in a visual stimulus, said device allowing the subject to directly see the visual stimulus.
Means for supporting at least one semi-reflective screen located proximate at least one eye of the subject, for reflecting light rays towards one or both eyes of the subject to provide a visual control signal. 11. The device of claim 10, having a visible light source carried by the support means. 20. The analyzing means calculates a standardized average response from each of the plurality of subjects' responses to the control signal only, and for each subject for simultaneous display of the control signal and visual stimulus. A means for determining the change in the magnitude of the component for each subject by subtracting the standardized mean response from the magnitude of the component of the measured EEG signal. The apparatus according to item 10.